Mild cognitive impairment is common in Parkinson's disease patients with normal Mini-Mental State Examination (MMSE) scores

Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA.
Parkinsonism & Related Disorders (Impact Factor: 3.97). 07/2008; 15(3):226-31. DOI: 10.1016/j.parkreldis.2008.05.006
Source: PubMed


Cognitive impairment occurs in the majority of Parkinson's disease (PD) patients, but little is known about detection of mild cognitive impairment (MCI) in this population. We report on the frequency and characteristics of cognitive deficits in PD patients with intact global cognition based on Mini-Mental State Examination (MMSE) performance.
One hundred and six PD patients with normal age- and education-adjusted MMSE scores (mean [SD] score=29.1 [1.1]) were administered standardized neuropsychological tests assessing memory, executive function, and attention. Impairment on a cognitive domain was a low score (i.e., >or=1.5 SD below the published normative mean) on at least two measures or tests (for memory and executive abilities) or a single measure (for attention).
Mild cognitive impairment was found in 29.2% of PD patients, with 17.9% demonstrating single domain and 11.3% multiple domain impairment. Memory and attention impairment were most common (15.1% and 17.0%, respectively), followed by executive impairment (8.5%). Depending on the measure of disease severity chosen, increasing age and disease severity, anti-anxiety medication use, and a suggestion for increasing severity of daytime sleepiness were independent predictors of cognitive impairment.
Cognitive deficits are common in PD patients with "normal" cognition based on MMSE performance, suggesting that MCI is under-recognized in clinical practice due to routine use of insensitive screening instruments. In contrast with some previous reports, early memory impairment may be as common as either executive or attentional deficits in PD. In addition, psychiatric medication use and daytime sleepiness may be reversible or treatable contributors to cognitive impairment.

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    • "From the practical point of view, more comprehensive language and memory testing limits the number of tests that can be devoted to executive function assessment and vice versa. In studies addressing PD-MCI published prior to PD-MCI guidelines [15], more extensive executive function testing was frequently applied, while other domains were tested in a more concise manner [52]. "
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    ABSTRACT: Cognitive deficits are one of the most common non-motor symptoms of Parkinson's disease (PD). Mild cognitive impairment (MCI) affects about 27% of non-demented PD patients. The high prevalence of PD-MCI and PD with dementia (PD-D) as well as increasing life expectancy in PD create the need for valid serial cognitive assessment in every PD clinic. In this paper we discuss the PD-MCI criteria and testing recommendations (Movement Disorder Society Task Force Guidelines) in the context of referral for neuropsychological assessment in clinical practice. The methodology suggested in the PD-MCI diagnosis guidelines is compared against PD-D testing recommendations. The requirement for at least10 cognitive tests to allow PD-MCI subtype to be determined is questioned, as a direct correspondence between low scores on a particular test and a domain-specific deficit cannot be assumed. As a variety of factors may underlie an impaired test score, the same test score may be affected by different deficits in different patients (e.g. a low verbal fluency score may be due to executive or language decline). A pathway approach to PD-MCI diagnosis is presented, in line with PD-D diagnostic guidelines. In cases where thorough screening results and clinical history are consistent with each other and presentation seems typical for PD-MCI, level I diagnosis could be established without neuropsychological assessment. However, when screening results diverge from the clinical history or the presentation is atypical, neuropsychological assessment should precede the diagnostic formulation.
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    • "For example, three participants who recalled falling at least monthly had no recent falls in their notes, and four had only a single fall recorded; five people without a MMSE in their notes had a MoCA suggesting moderate CI. Though using the MMSE and the MoCA to evaluate CI may have contributed to the differences in the rates and severity of CI noted in different parts of the current study, we agree with others [28] [29] who suspect MMSE underestimates the degree of cognitive dysfunction in PD. "
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    • "With regard to cognitive impairment in PD-MCI and PD-D, the frequencies of memory impairment in our study are very close to those reported by others: 13.3%–15.1%12,19 in PD-MCI patients, and 67.4% in PD-D patients.20 "
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